In natural convection heating systems, a heating element is warmed by the water that circulates within its pipes which intern warms the air surrounding the element. Hot air, being less dense than cool air, rises. The rising heated air draws cool air to flow in to take its place. This sets up a current of hot air that leaves the heater and which passively mixes throughout the room in order to heat the space to the desired temperature. These types of heating systems are very safe and there is a very low chance of getting burned.
Hot water heating systems operate on the premise of radiant heat. Water is heated to a relatively high temperature, typically from 140° F. to 200° F., by a central boiler and circulated through a series of pipes to a heating element, or series of heating elements, located within the space(s) to he heated. The typical hot water heating system is inefficiently controlled: it heats relatively large volumes of water for relatively small areas of heat transfer, circulates on for short periods of time, and stays off and at idle for comparatively long periods of time. The time periods when these systems are off and idling are typically two to three times longer than when circulating or “on”. While idling, these systems maintain operating boiler temperatures which results in actual operating efficiencies that are significantly less than peak optimal performance. Inefficient boiler controls, idle losses, poor heat transfer and the inability to effectively monitor and optimize temperature controls at the individual heat exchanger result in overall system efficiencies of under 50%.
Hydronic heaters are a type of natural convection heater that use heated water or another heated liquid to transfer heat from the primary heat source, generally a remotely located furnace, to the space that is being heated. They are typically positioned along the base of a wall, drawing in cool air at the lower end of the unit, heating it, and allowing the heated air to escape out of the top. Low external operating temperatures allow these types of heaters to be installed flush against a wall or baseboard without damage to the wall or baseboard. Hydronic heaters are usually installed when a house is being constructed or in conjunction with other renovations since they are required to be plumbed into a boiler or other remote heat source and work in conjunction with other heating units to evenly heat the entire structure and may require electrical integration making them difficult to add post-construction.
Electric heaters are another type of natural convection heater. They differ from hydronic heaters in that the primary heat source is an electric heating element located within each unit. They do not have to be connected with household plumbing. These heaters are wired into the household power supply, and most can also be controlled by an internal or remote thermostat. Electric baseboard heaters are far easier to install than hydronic heaters but the cost of operations are greater.
Natural convection heaters are easily blocked by furniture, curtains, or other obstructions, which prevent heated air from evenly circulating throughout a room. Because they heat by convection, natural convection heaters are passive and heat a space relatively slowly. Unlike more expensive forced air heating systems, which can be linked to an air conditioning system, natural convection heaters are necessarily separate from a cooling counterpart.
Significant cost reductions and improvements in overall system efficiencies can be achieved by improving boiler control strategies, intelligently controlling room temperature according to need, and/or altering the distribution of heat within the building to better meet demand.